Percutaneous arthrodesis method and system

ABSTRACT

A method and system for percutaneous fusion to correct disc compression is presented. The method has several steps, for instance, inserting a percutaneous lumbar interbody implant; positioning guide wires for each facet screw to be implanted; performing facet arthrodesis in preparation for the facet screws; fixating the plurality of facet screws; and optionally performing foramen nerve root or central decompression. The system includes an implant, an elongate cannulated insertion tool, and an elongate lockshaft positioned within the insertion tool.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/028,310 entitled “Percutaneous Arthrodesis Method And System” filedon Feb. 16, 2011.

FIELD OF THE INVENTION

Presented herein is a percutaneous arthrodesis method and system. Morespecifically, a method and system for minimally invasive 3-point fusionis presented.

BACKGROUND OF THE INVENTION

There are several procedures available to patients with degenerativespine conditions. For example, Anterior Lumbar Interbody Fusion (“ALIF”)has been performed by surgeons since the 1950's. In an ALIF procedure,the disc space is fused by approaching the spine through the abdomen. Inthe ALIF approach, a three-inch to five-inch incision is made on theleft side of the abdomen and the abdominal muscles are retracted to theside. Since the anterior abdominal muscle in the midline (rectusabdominis) runs vertically, it does not need to be cut and easilyretracts to the side. The abdominal contents lay inside a large sack(peritoneum) that can also be retracted, thus allowing the spine surgeonaccess to the front of the spine without actually entering the abdomen.There is also a less popular transperitoneal approach that accesses thespine through the abdomen. This adds a lot of unnecessary morbidity tothe procedure and therefore is used much less often.

Another technique is called Posterior Lumbar Interbody Fusion (“PLIF”).In the PLIF approach, the spine is accessed through a three-inch tosix-inch long incision in the midline of the back and the left and rightlower back muscles are stripped off the lamina and spinous process onboth sides and at multiple levels. After the spine is approached, thelamina and spinous process is removed, which allows visualization of thenerve roots. The facet joints, which are directly over the nerve roots,may then be undercut to give the nerve roots more room. The nerve rootsare then refracted to one side and the disc space is cleaned of the discmaterial. A bone graft, or an interbody cage, is then inserted into thedisc space and the bone grows from vertebral body to vertebral body.

Still another procedure is a Transforaminal Lumbar Interbody Fusion(“TLIF”). By removing the entire facet joint, visualization into thedisc space is improved and more disc material can be removed. It shouldalso provide for less nerve refraction. Because one entire facet isremoved, it is only done on one side. Removing the facet joints on bothsides of the spine would result in too much instability. With increasedvisualization and room for dissection, a larger implant and/or bonegraft can be used. Although this has some improvements over a PLIFprocedure, the anterior approach, in most cases still provides the bestvisualization, most surface area for healing, and the best reduction ofany of the approaches to the disc space.

There are other approaches know in the art, as well. For instance,Direct Lateral Interbody Fusion, Axial Lumbar Interbody Fusion using atranssacral approach, and the like. Those skilled in the art willappreciate that these and other known procedures have benefits, as wellas disadvantages.

There are also many types of stabilization systems available. One typeof spinal stabilization system includes screws and connecting rods whichcan be used for stabilizing many spinal conditions including, forexample, degenerative disc disease, scoliosis, spondylolithisis andspinal stenosis. In these systems, a bone screw (e.g., pedicle screw) istypically anchored into each vertebral body to be stabilized and a rigidconnecting rod mounted to the screws to fix the vertebrae in aparticular relative position.

Another type of spinal stabilization system includes interbody implants.Some of these implants are bone, PEEK, solid titanium or similarnon-bone implant material and some are hollow implants that provide forinclusion of a bone graft or other suitable material to facilitate bonyunion of the vertebrae.

Interbody implants can be inserted into the disc space through ananterior, posterior or lateral approach. In some systems, the implantsare inserted into a bore formed between adjacent vertebral bodies in thecortical endplates and can extend into the cancellous bone deep to thecortical endplates. Implant size is typically selected such that theimplants force the vertebrae apart to cause tensing of the vertebralannulus and other soft tissue structures surrounding the joint space.Tensing the soft tissues surrounding the joint space results in thevertebrae exerting compressive forces on the implant to maintain theimplant in place.

Accordingly, there is a continuing need for improved vertebralstabilizing devices and methods. The system and apparatuses describedherein are directed to addressing these needs.

SUMMARY OF THE INVENTION

Presented herein are a system and method for percutaneous fusion tocorrect disc compression. In one aspect, the system comprises an implantdefining at least one implant aperture, an elongate cannulated insertiontool defining an interior insertion tool pathway, and an elongatelockshaft positioned therein the insertion tool pathway and defining alongitudinal interior lockshaft pathway.

The method comprises several steps, which may or may not be performed inthe particular order discussed. As one skilled in the art canappreciate, the methods herein are not meant to be limited and onlyserve as a description of the method in its best known manner.

The method, in one aspect, comprises making an incision to access adesired spinal motion segment, locating a path to the disc space at thedesired target level, inserting a guide wire, inserting a spinal implantinto the disc space at a desired position, removing the guide wire, andfixating a portion of the desired spinal motion segment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the preferred embodiments of the presentinvention will become more apparent in the detailed description in whichreference is made to the appended drawings wherein:

FIG. 1 is a perspective view of one aspect of an Lumbar Interbody Fusionsystem;

FIG. 2 is a partially exploded perspective view of the Lumbar InterbodyFusion system of FIG. 1;

FIG. 3 is a side elevational view of the Lumbar Interbody Fusion systemof FIG. 1;

FIG. 4 is a cut-away side elevational view Lumbar Interbody Fusionsystem of FIG. 1, cut along line 4-4 of FIG. 3;

FIG. 5 is a plan view of the Lumbar Interbody Fusion system of FIG. 1;

FIG. 6 is a perspective view of one aspect for an implant used in aLumbar Interbody Fusion system;

FIG. 7 is a plan view of the implant of FIG. 6;

FIG. 8 is front elevational view of the implant of FIG. 6;

FIG. 9 is a rear elevational view of the implant of FIG. 6;

FIG. 10 is a side elevational view of the implant of FIG. 6;

FIG. 11 is a perspective view of one aspect for an implant used in aLumbar Interbody Fusion system;

FIG. 12 is a plan view of the implant of FIG. 11;

FIG. 13 is front elevational view of the implant of FIG. 11;

FIG. 14 is a rear elevational view of the implant of FIG. 11;

FIG. 15 is a side elevational view of the implant of FIG. 11;

FIG. 16 is a perspective view of one aspect of a percutaneousarthrodesis method, showing the step of positioning a nerve monitoringprobe with a transfer sleeve through Kambin's triangle;

FIG. 17 is a perspective view of the method of FIG. 16, showing the stepof advancing the transfer sleeve to contact a portion of the annulus forremoval of the probe;

FIG. 18 is a perspective view of the method of FIG. 16, showing the stepof removing the nerve monitoring probe, leaving the transfer sleeve inplace;

FIG. 19 is a perspective view of the method of FIG. 16, showing the stepof inserting a guide wire through the transfer sleeve to maintain a pathto the disc space;

FIG. 20 is a perspective view of the method of FIG. 16, showing the stepof removing the transfer sleeve and leaving the guide wire in place;

FIG. 21 is a perspective view of the method of FIG. 16, showing the stepof advancing a dilator over the guide wire;

FIG. 22 is a partially transparent perspective view of the method ofFIG. 16, showing the step of pushing a dilator into the disc space todistract the vertebral bodies;

FIG. 23 is a partially transparent perspective view of the method ofFIG. 16, showing the step of positioning an access portal into the discspace;

FIG. 24 is a partially transparent perspective view of the method ofFIG. 16, showing the step of removing the dilator and the guide wire,leaving the access portal in place;

FIG. 25 is a partially transparent perspective view of the method ofFIG. 16, showing the step of performing a discectomy and decorticatingthe vertebral endplates by first drilling to access the nucleus;

FIG. 26 is a partially transparent perspective view of the method ofFIG. 16, showing the step of performing a discectomy and decorticatingthe vertebral endplates by rotating a disc shaper;

FIG. 27 is a partially transparent perspective view of the method ofFIG. 16, showing the step of performing a discectomy and decorticatingthe vertebral endplates by grasping disc material with a Pituitaryrongeur;

FIG. 28 is a partially transparent perspective view of the method ofFIG. 16, showing the step of performing a discectomy and decorticatingthe vertebral endplates by using a disc cutter;

FIG. 29 is a partially transparent perspective view of the method ofFIG. 16, showing the step of introducing a bone graft through a portalusing a tube and plunger system;

FIG. 30 is a partially transparent perspective view of the method ofFIG. 16, showing the step of re-introducing a guide wire through theaccess portal;

FIG. 31 is a perspective view of the method of FIG. 16, showing theremoval of the access portal, leaving the guide wire in place;

FIG. 32 is a partially transparent perspective view of the method ofFIG. 16, showing the step of using the guide wire for insertion of atrial implant;

FIG. 33 is a partially transparent perspective view of the method ofFIG. 16, showing the step of connecting the implant to the insertiontool and following the guide wire to insert implant;

FIG. 34 is a perspective view of the method of FIG. 16, showing the stepof using the dilator to locate a path to the appropriate facet joint;

FIG. 35 is a partially transparent perspective view of the method ofFIG. 16, showing the step of using a dilator as a guide for introducingthe guide wire to a depth just beyond the anticipated depth of the facetscrew;

FIG. 36 is a partially transparent perspective view of the method ofFIG. 16, showing the step of introducing an access portal over thedilator for facet arthrodesis;

FIG. 37 is a partially transparent perspective view of the method ofFIG. 16, showing the step of introducing a drill via the portal to drillthrough a portion of the facet joint to prepare for insertion of a facetscrew;

FIG. 38 is a partially transparent perspective view of the method ofFIG. 16, showing the step of introduction of the facet screws; and

FIG. 39 is a partially transparent perspective view of the method ofFIG. 16, showing one aspect of a facet screw in place.

DETAILED DESCRIPTION OF THE INVENTION

The present systems and apparatuses and methods are understood morereadily by reference to the following detailed description, examples,drawing, and claims, and their previous and following description.However, before the present devices, systems, and/or methods aredisclosed and described, it is to be understood that this invention isnot limited to the specific devices, systems, and/or methods disclosedunless otherwise specified, as such can, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Tothis end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspects of theinvention described herein, while still obtaining the beneficial resultsof the present invention. It will also be apparent that some of thedesired benefits of the present invention can be obtained by selectingsome of the features of the present invention without utilizing otherfeatures. Accordingly, those who work in the art will recognize thatmany modifications and adaptations to the present invention are possibleand can even be desirable in certain circumstances and are a part of thepresent invention. Thus, the following description is provided asillustrative of the principles of the present invention and not inlimitation thereof.

As used throughout, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise. Thus,for example, reference to “a screw” can include two or more such screwsunless the context indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

Presented herein is a percutaneous arthrodesis method and system 10 tocorrect disc compression. The system comprises an implant 100 that, inone aspect, defines at least one implant aperture 110. The implant 100is sized for insertion between two adjacent vertebrae.

In another aspect, the system 10 also comprises an elongate cannulatedinsertion tool 200 defining an interior insertion tool pathway 210. Theinsertion tool 200 is configured to position the implant into thedesired position between two spinal vertebrae. In an exemplified aspect,the distal end 202 of the elongate cannulated insertion tool matinglyengages at least a portion of at least one external surface of theimplant.

As illustrated in FIG. 2, the insertion tool 200, in one aspect, has anelongate lockshaft 300 positioned therein the insertion tool pathway 210and defining a longitudinal interior lockshaft pathway 310, wherein adistal end 302 of the elongate lockshaft 300 selectively engages aportion of the implant. In an exemplified aspect, when the distal end302 of the elongate lockshaft is engaged with the implant 100, theinterior lockshaft pathway 310 and the implant aperture 110 aresubstantially coaxial. In this aspect, the implant aperture can extendtherethrough the implant, but does not necessarily do so. In thisaspect, however, the implant aperture and the interior lockshaft pathwayare configured for the acceptance of a guide wire.

The lockshaft 300, for example, can be configured to engage the implant100 in order to maintain rotational alignment of the implant withrespect to the insertion tool. In this aspect, rotation of the elongatecannulated insertion tool would, in turn, rotate the implant along itslongitudinal axis I_(L). In one aspect, at least a proximal portion ofthe implant aperture comprises internal threads 120 and at least aportion of the distal end of the elongate lockshaft comprises externalthreads 320 that mate with the internal threads 120 of the implantaperture 110.

In one exemplified aspect, a handle 220 can be positioned in a proximalportion 204 of the elongate cannulated insertion tool 200. The handle220 provides visual means to determine the rotational orientation of theimplant 100. Of course, other visual means for determining orientationcan also be employed. For example, and not meant to be limiting, thecannulated insertion tool can comprise markings or etchings along thelength of the shaft. The handle also provides the practitioner with aneasy means with which to turn the implant after insertion.

As mentioned above, the elongate lockshaft 300 can engage the implantfor insertion and positioning. In some instances, it is beneficial forthe elongate lockshaft to be configured to translate longitudinallywithin the elongate cannulated insertion tool. In this aspect, once theelongate lockshaft attaches to a portion of the implant, the implant canbe drawn into tighter engagement with the elongate cannulated insertiontool. In one exemplified aspect, the proximal end 204 of the elongatecannulated insertion tool comprises internal threads 230 and at least aportion of a proximal end 304 of the elongate lockshaft 300 comprisesexternal threads 325 that mate with the internal threads 230 of thecannulated insertion tool 200. As such, in this aspect, rotation of thelockshaft in a clockwise direction moves the lockshaft longitudinallywithin the cannulated insertion tool in a first direction and rotationof the lockshaft in a counterclockwise direction moves the lockshaft 300longitudinally within the cannulated insertion tool in a second, opposeddirection. In a further aspect, a knob 340 is positioned on a portion ofthe proximal end 304 of the lockshaft to enable the rotation of thelockshaft about its longitudinal axis L_(L). Other methods oftranslating the lockshaft longitudinally within the cannulated insertedare also contemplated.

In addition to the threaded engagement of the lockshaft 300 and theimplant 100, in one aspect, the distal end 202 of the elongatecannulated insertion tool is configured to mate with at least a portionof the proximal end 104 of the implant so that they remain in rotationalalignment. In one aspect, the distal end 202 is saddle-shaped, whereportions of the implant fit in the seat of the saddle, as illustrated inFIGS. 11-15. With reference to FIGS. 11 and 13, the proximal end 104 hasa threaded opening larger than the non-threaded opening at the distalend 102 shown in FIG. 14. The threaded opening configured to receive athreaded portion of a cannulated insertion tool for the passing of aguide wire through the non-threaded opening.

Various shapes and sizes for the implant are contemplated. In oneaspect, the implant comprises a substantially bullet shaped distal end102 and a longitudinal axis IL substantially coaxial with the implantaperture. The bullet shape is an atraumatic tapered distal end. Thetapered distal end has a profile of a frustoconical or an ellipticparabolic shape or between the two. This can mean that the distal end102 is a frustoconical or an elliptic parabolic, conical, or a shape inbetween the two. Such shapes enable the implant to displace the exitingnerve root in an atraumatic fashion. Where the distal end of theelongate cannulated insertion tool is saddle shaped, the proximal end104 of the implant 100 can be shaped matingly. Similarly, the proximalend of the implant can comprise a convex cylindrical surface, while thedistal end 202 of the elongate cannulated insertion tool 200 cancomprise a correspondingly concave cylindrical surface. Other matingsurfaces are also contemplated.

As illustrated in FIG. 10, the implant can also have two opposinglongitudinal gripping facets 130 each defining a ridged surface 132. Theridged surfaces are meant to assist with the implant's ability to gripthe adjacent bone structure. In one aspect, the ridges 132 are angledrearwardly in order to assist in preventing the implant 100 from backingout.

Sometimes, it is beneficial to have the means with which to promote bonegrowth and/or fusion. In one aspect, the implant further defines animplant cavity 140 in communication with the implant aperture andsubstantially open to at least one, or both, of the gripping facets 130.In this aspect, bone graft material or bone cement can be introducedinto the implant cavity 140. The bone graft material can be, forexample, autologous bone, allograft bone, bone substitute,osteoinductive agents, and the like.

The implant itself comprises a biocompatible material, capable of beinginserted into the body. In one aspect, the bio-compatible material isselected from the group consisting of PolyEtherEtherKetone, ceramic,allograft bone, and PolyEtherEtherKetone with BaSO₄. Other biocompatiblematerials are also contemplated.

Also presented herein is a percutaneous fusion method to correct disccompression. The method, in one aspect, comprises making aposterolateral incision to access the desired spinal motion segment;determining a target level of the disc space 402 between adjacentvertebral bodies 400 for implantation of an implant; locating a path tothe disc space at the target level; inserting a guide wire 440 tomaintain a path to the disc space 402; sliding the spinal implant alongthe guide wire 440 to position it into the disc space at the desiredposition; removing the guide wire; and fixating at least a portion ofthe desired spinal motion segment. As best illustrated in FIG. 33 andFIGS. 9-14, this method is achieved by using a spinal implant comprisinga body having a distal end, a proximal end, and a longitudinal axis,wherein the distal end being an anterior or leading portion of the bodyfirst to enter a disc space on insertion. The implant is sized for fullinsertion between two adjacent vertebrae. The spinal implant has asubstantially square or substantially rectangular cross section midwayfrom the proximal or distal end with height to width ratio in a range of1:1 to 2:1. The body has a length extending from the distal end to theproximal end and opposing sides or walls extending between the distaland proximal ends to support the adjacent vertebrae on opposing upperand lower surfaces. The length is greater than the width or the heightof the body of the implant and extends along the longitudinal axis anddefining at least one implant aperture therethrough. The body is alignedwith the longitudinal axis. The at least one implant aperture being incommunication with a proximal threaded opening and a distal smoothopening. The distal smooth opening is closely sized to slide along adiameter of the guide wire, as shown. The openings are in alignment withone another to allow the passage of a guide wire therethrough the bodyof the spinal implant to be coaligned with an insertion axis of theguide wire to prevent tissue entering the distal end opening as theanterior or leading portion distal end is being inserted into the discspace. The implant is configured to slide along a path maintained by theguide wire. The distal end is an atraumatic tapered distal end, thetapered distal end having a profile having a cross section along thelength of the body of a frustoconical shape or an elliptic parabolicshape, wherein the implant is sized to tense the soft tissue withoutdamaging the nerve to reestablish the normal disc height of the twoadjacent vertebral bodies; and the implant having a height and a lengthsized to accommodate being evenly spaced on each side of the spinousprocess of the two adjacent vertebral bodies.

This first step comprises making a posterolateral incision to access thedesired spinal motion segment. In one aspect, the initial access pointcan be made through Kambin's Triangle 410. Kambin's Triangle, as thoseskilled in the art will appreciate, is the site of surgical access forposterolateral endoscopic discectomy. It is defined as a right triangleover the dorsolateral disc. The hypotenuse is the exiting nerve, thebase (width) is the superior border of the caudal vertebra, and theheight is the traversing nerve root.

The method also comprises determining the target level of the disc spacebetween adjacent vertebral bodies 400. Once the target level isestablished, the method comprises locating a path to the disc space atthe target level. This can be accomplished, for example, using a nervemonitoring probe 420 with a transfer sleeve 430. The nerve monitoringprobe can measure the proximity of the exiting nerve root. Oncemeasured, in an exemplified aspect, the probe 420 can then be removed,leaving the transfer sleeve 430 in place. In one aspect, the nervemonitoring probe comprises an EMG Navigation system, comprising ablunt-tipped monopolar probe and an exchange cannula.

The method also comprises inserting a guide wire through the transfersleeve to maintain a path to the disc space. In one aspect, the guidewire 440 can be a Kirschner wire or k-wire. After insertion of the guidewire, one aspect of the method comprises removing the transfer sleeveand placing a dilator 450 over the guide wire. The dilator 450 can bedriven into the disc space 402 to distract the vertebral bodies 400.

In one aspect, the next step comprises positioning an access portal 460into the disc space. For instance, in one exemplified aspect, thesurgeon can slide the access portal 460 over the dilator and use animpact sleeve with a mallet to lodge the portal into the disc space. Thedilator and guide wire can then be removed, leaving the access portal inplace.

In a further aspect, the method can comprise performing a discectomy anddecorticating the vertebral endplates. In an exemplified aspect, a drill470 can be used to access the nucleus and prepare the area for otherdiscectomy instruments. For example, and not meant to be limiting, adisc shaper 480, as shown in FIG. 26, can be used for endplatepreparation. The surgeon may elect to remove some of the loose discmaterial at this point. As such, a pituitary rongeur 490 can be used. Inanother aspect, a disc cutter 500, as shown in FIG. 28, can be used toaccomplish a thorough discectomy. After which, the pituitary rongeur 490can be used again to remove remaining disc remnants.

In one aspect, a bone graft (not shown) can then to be introduced. Asone skilled in the art can appreciate, this can be accomplished throughthe portal using a tube and plunger 510 system. In one aspect, the bonegraft is a sentinel bone graft. The surgeon can then re-introduce theguide wire 440 and remove the access portal 460.

With input from pre-surgical radiographic film, the next step cancomprise determining the height of an adjacent level healthy disc toassist with the selection of an appropriately sized implant. The size ofthe implant 100 can be confirmed with a paddle trial or a solid bodytrial. To do so, the surgeon can first insert the trial implant along apath, guided by the guide wire. An insertion tool 200, as describedherein above, may be used. Once inserted, if the selected trial implantcannot be rotated into an erect position, the surgeon can then step downto a smaller size. Alternately, if the selected trail can be rotatedinto an erect position without much frictional resistance, the surgeoncan choose the next larger size. Several iterations may be necessary toachieve the correctly sized implant. As shown in FIGS. 6-10, the implant100 has an elongated body, the body having a length extending from thedistal end to the proximal end. The length is greater than the height orthe width of the body of the implant 100. The body has opposing sides orwalls extending therebetween the proximal and distal ends to support theadjacent vertebrae on opposing upper and lower surfaces. As shown, fromthe proximal end 104 view of FIG. 8 or 13 or from a distal end 102 viewof FIG. 9 or 14, the substantially square or rectangular cross sectionmidway from the two ends 102, 104 as seen in FIGS. 7 and 10 and 12, and15 respectively. The proper height to width ratio is in a range of 1:1to 2:1 as illustrated. This ratio accommodates the ability to rotate theimplant 100 by 90 degrees if desired. The resultant selected height ofthe implant 100 is based on the height of an adjacent level healthydisc. As noted above, the height of the implant 100 replicates thehealthy disc height. The inserted implant, when fully inserted, tensesthe soft tissue without damaging the nerves while reestablishing thenormal disc height of the vertebral bodies.

As described herein above, in one aspect, the implant 100 comprises animplant cavity 140. As such, the method comprises, after determining theappropriate implant height and length from the trials, loading graftmaterial into the implant cavity and connecting the implant to theinsertion tool and following the guide wire to insert the implant.Imaging technology can be used to verify the correct location of theimplant. In one aspect, fluorographic imaging can be used to watchradiographic markers in order to determine the correct location of theimplant. In one aspect, as determined by the surgeon, when the imagesshow the radiographic markers evenly placed on each side of the spinousprocesses, the implant is placed properly. Once the implant is placedproperly, the surgeon can then turn the implant 90 degrees and releaseit from the insertion tool 200.

The next step of the method comprises fixating at least a portion of thedesired spinal motion segment. In one aspect, this comprises fixating aportion of the facet of the desired disc with a facet screw 520. In oneaspect, the facet screw can be a Spartan Facet Screw. For fixation ofL5-S1, L4-L5, and/or L3-L4, the surgeon can make an incisionsubstantially proximate the spinous process of L3. Then, the methodcomprises using the dilator 450 to locate a path to the appropriateinferior articular process. The dilator is used as a guide forintroducing the guide wire. In one aspect, the guide wire is deliveredby using an electric drill, which delivers the guide wire to a depthjust beyond the anticipated depth of the facet screw. Alternate fixationmethods include, but are not limited to, pedicle screws, spinous processclamps, and other known fixation methods.

In another aspect, the method also comprises further attaching a neuralmonitoring lead to the guide wire 440 and stimulating it to a level upto 10 mA to detect the proximity to the exiting nerve roots and caudaequina. Next, the surgeon can place guide wires for all of the facetscrews. The dilators could then be removed, leaving the guide wires inplace.

The next step in the method comprises performing facet arthrodesis byusing a rasp (not shown) capable of removing cartilage, decorticatingthe joint surfaces. In one aspect, an Amendia Spear disposable rasp maybe used. In one aspect, the rasp can comprise a substantially Y-shapeddistal end to conform to a portion of the positioned guide wire and movethereabout the guide wire 440. The method comprises using the sameincision as with the interbody approach, and inserting a dilator 450 totarget the lateral aspect of the facet joint 412. An access portal is,then, introduced over the dilator. Once the portal is positioned, thedilator may be removed. At this point, the appropriate sized rasp can beintroduced via the portal 460 to remove cartilage and to decorticate thejoint surfaces. After the rasp is removed, the surgeon can, next, load agraft into the delivery tube and insert it into the prepared facet joint412. In another aspect, this process is repeated through a new incisionin a similar location on the contralateral side, targeting thecontralateral facet.

In still another aspect, the next step of the method comprises fixatingthe facet screws. In one aspect, the facet screws may comprise a SpartanFacet Screw. First, the surgeon will re-insert dilators over each of theguide wires. Then, access portals will be introduced via each of thedilators. The dilators can then be removed, leaving the guide wires inplace. The surgeon will then deliver the drill bit 470 over the guidewire, penetrating the superior articular process of the inferiorvertebral body and drill into the pedicle of the inferior vertebralbody.

In one aspect, the facet screws can, then, be introduced, for example,with a screw retaining driver. The method can comprise driving a lagscrew to a desired depth to compress the facet joint onto the graft.Alternately, a facet screw with threads along the full length may beused to immobilize the facet joint. At this point, the retaining drivercan be released from the implanted screw and the steps of this aspectcan be repeated for all levels, bilaterally.

In yet another aspect, the method further comprises performing a foramennerve root or central decompression, if the surgeon determines that thisstep is required.

Although several embodiments of the invention have been disclosed in theforegoing specification, it is understood by those skilled in the artthat many modifications and other embodiments of the invention will cometo mind to which the invention pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is thus understood that the invention is not limited to the specificembodiments disclosed herein above, and that many modifications andother embodiments are intended to be included within the scope of theappended claims. Moreover, although specific terms are employed herein,as well as in the claims which follow, they are used only in a genericand descriptive sense, and not for the purposes of limiting thedescribed invention, nor the claims which follow.

What is claimed is:
 1. A system for performing spine surgery,comprising: a spinal implant and a cannulated insertion tool; the spinalimplant comprising a body having a distal end, a proximal end, and alongitudinal axis, the distal end being an anterior or leading portionof the body first to enter a disc space on insertion, the spinal implantbeing sized for full insertion between two adjacent vertebrae, thespinal implant having a substantially square or substantiallyrectangular cross section midway from the proximal or distal end with aheight to width ratio in a range of 1:1 to 2:1, the body having a lengthextending from the distal end to the proximal end and opposing sides orwalls extending between the distal and proximal ends to support theadjacent vertebrae on opposing upper and lower surfaces, the lengthbeing greater than the width or the height of the body of the spinalimplant and extending along the longitudinal axis, the body beingaligned with the longitudinal axis and defining at least one implantaperture therethrough, the at least one implant aperture being incommunication with a proximal threaded opening and a distal smoothopening, the openings being in co-alignment with one another andconfigured to allow the passage of a guide wire along an insertion axisof the guide wire, the distal smooth opening being closely sized toslide along a diameter of the guide wire in order to prevent tissueentering the distal smooth opening as the distal end is being insertedinto the disc space and as the body slides along a path maintained bythe guide wire, the distal end being an atraumatic tapered distal end,the distal end having a profile having a cross section along the lengthof the body of a frustoconical shape or an elliptic parabolic shape,wherein the spinal implant is sized to tense the soft tissue withoutdamaging the nerve to reestablish the normal disc height of the twoadjacent vertebral bodies, wherein the height and length of the spinalimplant are sized to accommodate being evenly spaced on each side of thespinous process of the two adjacent vertebral bodies, and wherein theproximal end of the body has an external surface having a convex profileconfigured to mate with the cannulated insertion tool; the cannulatedinsertion tool comprising a distal end with a saddle-shaped concavityand an internal lockshaft positioned therein in a cannulated insertiontool pathway, the internal lockshaft having a threaded distal end opento receive the guide wire passing through the body and being configuredto threadingly engage the proximal threaded opening of the spinalimplant when drawn into tightened engagement by rotation of the internallockshaft, and wherein the convex profile at the proximal end of thebody is fitted into a seat of the saddle-shaped concavity such thatrotation of the cannulated insertion tool correspondingly rotates thespinal implant as the guide wire maintains the path along the insertionaxis.
 2. The spinal implant of claim 1, wherein the body further definesan implant cavity in communication with the implant aperture and open toat least one of the two opposing surfaces.
 3. The spinal implant ofclaim 1, comprising bio-compatible material.
 4. The spinal implant ofclaim 3, wherein the bio-compatible material is selected from the groupconsisting of PolyEtherEtherKetone, ceramic, allograft bone, andPolyEtherEtherKetone with BaSO.sub.4.
 5. The spinal implant of claim 1,wherein the two opposing surfaces for supporting the adjacent vertebraeare planar.
 6. The spinal implant of claim 1, wherein the two opposingsurfaces each have longitudinal gripping facets defining a ridgedsurface.
 7. The spinal implant of claim 1, wherein the proximal endopening is threaded with internal threads, and the proximal opening islarger than the distal opening.
 8. The spinal implant of claim 1,wherein the distal end shape is a frustoconical shape.
 9. A system forperforming spine surgery, comprising: a spinal implant and a cannulatedinsertion tool; the spinal implant comprising a body having a distalend, a proximal end, and a longitudinal axis, the distal end being ananterior or leading portion of the body first to enter a disc space oninsertion, the spinal implant being sized for full insertion between twoadjacent vertebrae, the spinal implant having a substantially square orsubstantially rectangular cross section midway from the proximal ordistal end with a height to width ratio in a range of 1:1 to 2:1, thebody having a length extending from the distal end to the proximal endand opposing sides or walls extending between the distal and proximalends to support the adjacent vertebrae on opposing upper and lowersurfaces, the length being greater than the width or the height of thebody of the spinal implant and extending along the longitudinal axis,the body being aligned with the longitudinal axis and defining at leastone implant aperture therethrough, the at least one implant aperturebeing in communication with a proximal threaded opening and a distalsmooth opening, the openings being in co-alignment with one another andconfigured to allow the passage of a guide wire along an insertion axisof the guide wire, the distal smooth opening being closely sized toslide along a diameter of the guide wire in order to prevent tissueentering the distal smooth opening as the anterior or leading portion isbeing inserted into the disc space and as the body slides along a pathmaintained by the guide wire, the distal end being an atraumatic tapereddistal end, the distal end having a profile having a cross section alongthe length of the body of a frustoconical shape or an elliptic parabolicshape, wherein the spinal implant is sized to tense the soft tissuewithout damaging the nerve to reestablish the normal disc height of thetwo adjacent vertebral bodies, and wherein the height and length of thespinal implant are sized to accommodate being evenly spaced on each sideof the spinous process of the two adjacent vertebral bodies, wherein theproximal end of the body has an external surface having a convex profileconfigured to mate with the cannulated insertion tool; the cannulatedinsertion tool comprising a distal end with a saddle-shaped concavityand an internal lockshaft positioned therein in a cannulated insertiontool pathway, the internal lockshaft having a threaded distal end opento receive the guidewire passing through the body and being threadinglyengaging the proximal threaded opening of the spinal implant when drawninto tightened engagement by rotation of the internal lockshaft, andwherein the convex profile at the proximal end of the body is fittedinto a seat of the saddle-shaped concavity such that rotation of thecannulated insertion tool correspondingly rotates the spinal implant asthe guide wire maintains the path along the insertion axis, wherein thebody further defines an implant cavity in communication with the implantaperture and open to at least one of the two opposing surfaces.